Wednesday, December 16, 2009

Philippine Volcano on the War Path

Experts Expect Mayon Volcano to Erupt In Next Couple of Days or Weeks

Mayon Volcano in Albay, PhilippinesImage via Wikipedia

The Ring of Fire may unleash its fiery wrath in the Philippines, as the Mayon Volcano rumbles and roars.

About 50,000 locals were evacuated around the island nation’s most active volcano today, as it sent orange and red molten lava cascading down its sides, while off-white – but burning hot – clouds of ash and molten ambers fell from the sky.

The Philippine Institute of Volcanology and Seismology – which has kept a watchful eye on Mayon for years – warned residents they expect the volcano to erupt within the month. They detected 83 volcanic quakes, mostly tremors due to falling rocks.

Rockslides are not uncommon on mountainous terrain, however where volcanoes are the focal point, they are signs of much more troubling geological disturbances deep within the Earth’s crust.

Volcanoes – such as Mayon – are formed much as glaciers are, by platonic movements of the planet’s land masses. All of our continents are actually floating on the surface of the Earth on giant “plates” of land, which float on the Earth’s mantle made of liquid lava.

As these plates move across the Earth, they collide into one another. When two plates brush up against one another, enormous pressure builds, until the force is so great, one of the plates literally explodes out, and either slips underneath the obstructing plate, slides up and over the obstructing plate, or slides alongside the obstructing plate.

Any form of movement displaces the land mass on both plates, creating a shockwave which ripples up and out great distances. The area where the pressure is released, causing the slip or the slide is called the epicenter of the shockwave – the shockwave itself is felt as an earthquake.

Not all platonic movements result in earthquakes. All land on our planet is constantly moving – so slowly it is barely noticeable. We’re talking literally millimeters a day – but even this small amount of force is enough to cause dramatic changes to the landscape over time.

Over thousands of years, flat sprawling lands may turn into hilly valleys. Thousands of years later, these hills are now mountain ranges – in the northern regions they are capped with snow and ice, but along the Ring of Fire, they are capped with lava domes.

The Ring of Fire is a horseshow-shaped area circling the Pacific Basin spanning some 40,000 KM. This ring is bound by tectonic plates, which is why it is home to over 75 percent of the world’s active and dormant volcanoes – 90 percent of the world’s earthquakes happen within this region too. At last count, there were 452 volcanoes in the Ring of Fire.

As the tectonic plates crash and collide, they build mountains, and the pressure from deep within the Earth’s molten crust is forced up into these mountains. As the molten lava bubbles up to the surface, some is released along the base and sides of these.

At the top of the mountain, bubbling lava cools and hardens at the very top, creating a rock-hard lava dome.

The pressure continues to build throughout the mountain, as the tectonic plates move the Earth around the mountain, constantly forcing more and more pressurized lava up and into the mountain.

Occasionally, if the pressure is too great, weaker areas of the mountain will explode, venting ash, rock and some lava. But over time, these natural vents may clog, cool and harden back into solid rock.

This creates pressure back down the volcano, which collides with the pressurized tectonic plate movements. When the pressure becomes too much, a plate may slip or slide, causing an earthquake. This is why earthquakes near volcanoes are a good sign the volcano is about to erupt – they are an indicator of the forces within the large mountain.

Eventually, the pressure all around may be too great for the mountain to contain, and rupture the lava dome at the top, causing a massive and sudden release of pressure – think of the force released from an exploding Champaign bottle – only much larger.

Or, occasionally, the earthquakes caused by all the pressure may be strong enough to actually rupture the lava dome at the top of the volcano, causing the sudden and massive eruption of the mountain.

As the volcano erupts into a fire ball, it shoots burning hot ash hundreds of feet into the air, as searing hot molten lava flows up and out, destroying everything in its path.

The Mayon volcano has killed over 1,200 people in its most violent eruption in 1814 – it’s last eruption occurred in 1993 – but many more could die this time around, as far more people call the neighboring 45 towns and cities circling the dangerous mountain’s base home.

Some of the cities in the “kill zone” for this 2,464 meter (8,077 foot) high massive mass of rocks the size of houses, and oozing hot lava flows include Legazpi, Ligao, Tobaco, Daraga, Camali, Guinobatan, Malililipot and Santo Domingo. The small island nation’s capital of Manila is about 500 kilometers (about 300 miles) from the six kilometer (3.7 mile) kill zone radiating out from the Mayon volcano. Anything within this area – and possibly even further – would be wiped off the planet if the volcano exploded.

The Mayon volcano has erupted 49 times since records of the large active mountain have been kept (since 1616). If it blows it’s lid as scientists are predicting, residents may have little to no warning, as predicting volcanic eruptions is not an exact science, that’s why 47, 285 people are being evacuated over the next 72-hours.

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